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Table 1 Design features considered for assessment of risk of bias

From: Systematic reviews of observational studies of risk of thrombosis and bleeding in urological surgery (ROTBUS): introduction and methodology

Domain

Lower risk of bias

Higher risk of bias

Sampling and representativeness of the population

Consecutive patient recruitment or administrative database with random sampling

Non-consecutive patient recruitment or administrative database with non-random sampling

Study type

International multicenter; multicenter in one country; single center, not single surgeon

Single surgeon series

Source of information

Data abstracted by investigators from patient charts

Administrative database information

Thromboprophylaxis documentation

Reporting of patients’ thromboprophylaxis

No reporting of patients’ thromboprophylaxis

Diagnostic criteria

Objective confirmation of symptomatic venous thromboembolism

No objective confirmation of symptomatic venous thromboembolism

Loss to follow-up

Less than 20% loss to follow-up

20% or more loss to follow-up